Apple Watch stuck in power reserve mode

Is your Apple Watch charged past 10%? When the Watch gets fully charged, it should automatically come out of Power Reserve. And the Watch will not resume normal operations if the battery is below 10%. More info here: https://support.apple.com/en-us/HT204608#powerreserve

Have you tried push the crown and side button together while connected to the charger? Also just press the side button in to turn on.